@Test
    public void songMapperTest(){
        QueryWrapper<Song> queryWrapper = new QueryWrapper<>();
        queryWrapper.like("name","爱");
        List<Song> songs = songMapper.selectList(queryWrapper);
        for (Song s : songs) {
            System.out.println(s.toString());
        }
        Assert.assertThat(songs, Matchers.notNullValue());//assertThat断言后面介绍
    }
